Posts tagged brain
Does Brain Scanning Show Just the Tip of the Iceberg?
Brain scans + fMRI: What are we seeing and what are we missing?
Two new studies suggest that fMRI studies, the brain activity scans that give us those “thermal blob” images we are so used to, might be the equivalent of cracking an egg with a sledgehammer. You’ll see an effect, but it’s kind of a brute force blunt object, considering the detail of the job. At the same time, when observations are made outside of “normal” experimental time frames, unexpected and interesting results can show up.
From Neuroskeptic:
As an analogy, suppose that all you knew about your neighbours was from the noises that you heard through the wall. The shouts and screams would be loud enough to reach your eyes; the normal conversations and whispers wouldn’t. If you concluded that all your neighbours did was shout, not talk, you’d get a misleading picture of their relationship.
That’s the bad news. On the other hand, fMRI is clearly more powerful than most neuroscientists have realized, and this holds out hope for cracking some of the trickiest questions facing the field in the future, with larger studies and more sensitive techniques
“ Two research studies, co-led by UC Davis neurologist Charles DeCarli and conducted by an international team that included more than 80 scientists at 71 institutions in eight countries, has advanced understanding of the genetic components of Alzheimer’s disease and of brain development. Both studies appear in the April 15 edition of the journal Nature Genetics.”
Notes on Neurobiological Substrates of Punishment
- Impulsive punishment may relate to amygdala-based circuitry (AM/PAG, yellow), where there is associative learning between cues and outcomes.
- Instrumental punishment may be connected to striatal-mediated reinforcement for goal oriented actions. This type of punishment may lead to appetitive retributive goals (fascinating), possibly coming from the MFOC (medial orbitofrontal cortex), or from forward-planning areas of the prefrontal cortex which also plays a role in theory of mind (blue areas).
- These appetitive/instinctual actions may reinforce further action through the dorsomedial striatum (DMS,green) which if becoming “habit-based”, we’re then looking at reinforced action through dorsolateral striatum (DLS, red), which would likely indicate dopamine-dependent circuits.
[via: The Neurobiology of Punishment]
“ Scientists from the Center for Innovation in Science and Technology, University of Washington placed an array of 64 electrodes on the scalp of four people suffering from severe epilepsy. The initial aim of this study was to examine what is happening in the brain of these patients and thereby is causing seizures. At the same time the electrodes controlled the brain areas which are considered to be responsible for speech. These are motor cortex, Wernicke’s area and Broca’s area. These brain regions produce 40 phonemes (distinguished vocal sounds in speech) which structure the English language.”
“ You should eat salmon before a test, berries to prevent Alzheimer’s, or a vitamin supplement to increase your memory. You’ve heard the term “brain foods” since you were a kid, but how much do you really know about them? More importantly, is there really a way to boost your brain power just be eating a certain type of diet? We talked with two experts to unravel the myths and unpack the facts about how much food can really impact your brain.”
Just as your stomach, muscles, and heart feed on the nutrients that food supplies, so does the brain. The brain controls almost everything we do and when it takes in chemicals it can have an effect on how it works, both positively and negatively. While you can’t push your brain past a certain limit, chances are that your diet isn’t providing it with what it needs.
“ A Japanese-German collaboration has moved an experiment into the confines of a magnetic scanner to record the brain’s response to unseen stimuli. Rather than using erotic pictures, they projected a low-contrast grating that was drifting horizontally into one eye. It was surrounded by a scintillating ring in the same or in the opposite eye. In the latter case, the central stimulus became perceptually invisible. It disappeared. This experiment used what is known in the lingo as a 2 × 2 design. The scientists manipulated the visibility of the moving grating (two conditions); they also manipulated whether or not subjects attended to the grating (two conditions). They achieved the latter two conditions by asking them to monitor a series of single letters that appeared on the ring and to report the presence of a particular letter. On the other half of the trials, subjects were told to ignore these letters. In total, four conditions were tested.”
“ Why Not Map A Brain? What’s wrong with mapping the brain? In principle, nothing. It makes total sense. But there are practical difficulties: First, the task is enormous. There are 80 billion cells, connected in almost a hundred trillion ways. We could (using faster and faster computers) map all of them, but it would still take decades, (maybe centuries) to finish the job. Mapping even little hunks of brain takes years. Second, there’s the expense. Not just the millions of dollars necessary for computers, but the need for talented brain scientists to inspect and interpret the map for accuracy. Brain cells vary tremendously. Some stretch their tendrils across vast distances; others cuddle tightly with their neighbors. Some cell pathways are used often, some are used rarely. We don’t really know which is which. There may be invisible software that regulates activity among cells; finding, classifying and understanding what we see (and don’t see) will not be easy.”
“”Researchers from Georgetown University Medical Center and the University of Illinois – Chicago used an artificial 13-word language, Brocanto2, to describe a computer game. While the artificial language’s small vocabulary allowed subjects to learn it fairly quickly, its grammar was relatively sophisticated, mimicking the rules of Romance languages while diverging from the participants’ native English grammar. Next, the researchers separated 41 adults, who spoke only English, into two groups at random. One would study Brocanto2 through explicit, and the other through implicit, training. To standardize the brain scans, the participants all had to be right handed. […]
While both groups achieved similar proficiency in the artificial language, their brains weren’t as evenly matched. Only the brains in the immersion training group processed language like native speakers’ brains would. And even after five months of zero exposure to Brocanto2, the brain patterns in both groups only became more similar to those of native speakers.
Scientists claim brain memory code cracked
ScienceDaily (Mar. 9, 2012) — Despite a century of research, memory encoding in the brain has remained mysterious. Neuronal synaptic connection strengths are involved, but synaptic components are short-lived while memories last lifetimes. This suggests synaptic information is encoded and hard-wired at a deeper, finer-grained molecular scale.
In an article in the March 8 issue of the journal PLoS Computational Biology, physicists Travis Craddock and Jack Tuszynski of the University of Alberta, and anesthesiologist Stuart Hameroff of the University of Arizona demonstrate a plausible mechanism for encoding synaptic memory in microtubules, major components of the structural cytoskeleton within neurons.
Microtubules are cylindrical hexagonal lattice polymers of the protein tubulin, comprising 15 percent of total brain protein. Microtubules define neuronal architecture, regulate synapses, and are suggested to process information via interactive bit-like states of tubulin. But any semblance of a common code connecting microtubules to synaptic activity has been missing. Until now.
Original paper here.
